Hello, your problem is that Opengl blend functions expect the geometry to be ordered from furthest to nearest. That is the front(s) of your box are closest to the camera so they need to be drawn AFTER the sphere. You will need to break up the drawing of the box into what is in front of the sphere and what is behind it.

As an aside, I really wouldn't waste a lot of time learning the fixed function pipeline.

Is an excellent resource to learn modern opengl programming with shaders and such. Learning the old fixed function pipeline will (IMO) just frustrate you more when you move on. Also, most of it is deprecated and you run the risk of it not working well on new graphics cards.